Cardiovascular - BioGearshttps://biogearsengine.com/forums/categories/cardiovascular/feed.rss
Fri, 22 Feb 2019 15:01:30 +0000Cardiovascular - BioGearsen-CADefibrillationhttps://biogearsengine.com/forums/discussion/73/defibrillation
Fri, 01 Dec 2017 16:26:17 +0000NurNur73@/forums/discussionsAt first, sorry for my english, it's not very good and I hope that You understand me.Have you any actions to simulate defibrillation? Unfortunately, did not see this information in the documentation.

Thanks,NurNur]]>Proposed "variant" of Cardiovascular module without an explicit cardiac cyclehttps://biogearsengine.com/forums/discussion/12/proposed-variant-of-cardiovascular-module-without-an-explicit-cardiac-cycle
Wed, 18 Mar 2015 21:30:29 +0000acorbett12@/forums/discussionshttps://www.biogearsengine.com/forums/discussion/7/different-cardiovascular-models-for-different-clinical-problems-with-different-time-scales#latest), I see value in building a version of the engine that can run at higher simulated:real time ratios. With this goal in mind, I've spent some time evaluating the code and documentation to determine if and how it might be adapted to remove the explicit cardiac cycle.

The critical change, I believe, would be in the cardiovascular circuit. Currently the left and right ventricles are represented as capacitors, with time-varying compliance to represent the cardiac cycle (an elegant and well-known approach). Much of the code in, or called from, Cardiovascular::CardiacCycleCalculations() is concerned with calculating compliance at the current time-point in the cardiac cycle -- the cardiovascular circuit is then updated with these new compliances.

Based on the documentation for the Circuit Methodology (https://www.biogearsengine.com/documentation/a00008.html) it seems that it should be possible to replace the left and right ventricles with pump elements. Cardiovascular::CardiacCycleCalculations() would then be modified to calculate and update the pump output based on stroke volume and beats per minute, which themselves would be modified by drug effects, partial CO2, other factors [as in Cardiovascular::StartSystoleCalculations()]. (This would likely best be achieved by inheriting a new class, say CardiovascularNoCycle, from Cardiovascular and then overriding functions where needed).

With these changes it should be possible to run the engine with larger time steps and therefore higher simulated:real time ratios. My big concern here is how this will effect the cardiovascular circuit code. With larger time steps, the output of the ventricles (now represented as pumps) could change significantly within a single step. Would this cause instabilities in volume & pressure throughout the circuit? Would it be possible to determine a maximum allowable delta for pump output that would NOT cause instabilities? And might this maximum be so small so as to get us back to where we started?

I'm eager to hear feedback on these ideas from the Biogears designers and programmers. It will let me know whether I'm understanding the engine correctly, whether I'm on the right track for how to make such a modification, and if it's even possible.

And for those who've read this far and are still wondering why you'd ever want to remove the cardiac cycle, let me elaborate just a bit... The current engine, with explicit modeling of the cardiac cycle, is absolutely essential to simulate any clinical situation where detailed heart function is critical: heart attack, arrhythmia, massive hemorrhage, etc. And it is the perfect approach for any situation where you want to simulate at near real-time -- such as embedded software in a mannequin, or a trauma simulation running at near real-time. But this ability comes at a high cost of computational load and, I believe, makes the engine less useful for simulating clinical situations that play out over longer time frames and for which detailed heart function is less important -- such as poisonings, diabetic crises, kidney disease, infections, etc. For those, I'd like to simplify the modeling of the heart, while keeping all the other awesome benefits of the Biogears engine and its associated framework.